Drivers may encounter any of a variety of difficulties during their normal day-to-day commute, some quite inconsequential while others may be life threatening. Many of these problems arise due to simple vehicle malfunctions or driver errors. Driving conditions, especially those encountered during extreme weather, may also lead to an accident. Road debris is another leading cause of vehicle damage which, in many instances, may lead to a significant accident as a driver reacts to the debris and/or damage to their car.
While a conventional car is clearly susceptible to being damaged by road debris, hybrid and all-electric vehicles offer a unique challenge due to their inclusion of a rechargeable battery pack. Rechargeable batteries tend to be relatively unstable and prone to thermal runaway, an event that occurs when a battery's internal reaction rate increases to such an extent that it is generating more heat than can be withdrawn. If the reaction rate and generation of heat go unabated, eventually the heat generated becomes great enough to cause the battery and materials in proximity to the battery to combust. While thermal runaway is typically the result of a battery short or a manufacturing defect, damage such as that which may occur during an accident or when road debris dents or punctures the battery pack may also lead to a thermal runaway event.
Due to the risk of a battery pack fire, hybrid and electric vehicle (EV) manufacturers use a variety of techniques to shield their battery packs from the possible damage that may result from road debris or a vehicle collision. For example, in a vehicle using a relatively small battery pack such as a hybrid, the pack may be protected by placing it within the rear trunk, behind the rear seats, under the front seats, or in another comparatively well protected location. Vehicles utilizing large battery packs typically are forced to mount the pack under the car. To protect such a pack, a ballistic shield may be located between the road surface and the bottom of the pack as disclosed in U.S. Pat. Nos. 8,286,743 and 8,393,427.
Although the prior art teaches a variety of mounting techniques that can either be used to place the battery pack in a relatively protected region of a car or to otherwise shield the battery pack from potential harm, given the severity of the consequences accompanying a catastrophic battery pack event, further techniques for protecting an under-carriage mounted battery pack are desired. The present invention provides such a protection scheme.